After the Tohoku earthquake struck Japan at on March 11, 2011, there was a 30-minute lull before the devastating tsunami rushed ashore. Geophysicist Yehuda Bock from the Scripps Institute of Oceanography says that if his early warning system had been in place at the time, it could have used that lull to determine the magnitude of the earthquake and calculate the intensity of the subsequent tsunami, perhaps giving residents enough warning time to seek higher ground before the waves struck.

In a talk at the meeting of the American Geophysical Union on Tuesday, Bock and his colleagues at NASA and the National Oceanic and Atmospheric Administration (NOAA) presented their proposal for a sensor network that could provide early warnings for earthquakes, tsunamis, severe weather, and flash floods, providing life-saving information to first responders, local leaders, and the general public. The system combines GPS with equipment such as accelerometers and temperature and pressure sensors that can be added on to existing weather stations. During the talk, Bock said the rigs typically cost less than $5000 apiece.

Bock's sensors already have been installed at hundreds of sites across Southern California. And the SoCal sensor network has already been put to the test. In July 2013, NOAA used it to track a monsoon and predict flash floods, which can be deadly, across San Diego and the city of Oxnard. The sensors provided continuous real-time data about the levels of water vapor in the atmosphere and helped the National Weather Service send out accurate flash flood warnings, NOAA meteorologist Mark Jackson said.

The researchers think the network will also come in handy for forecasting earthquakes at California's San Andreas Fault, which is overdue for a big earthquake. If the system measures the strength of the primary (P) wave from an earthquake at the fault, they say, it can predict the timing and intensity of the secondary (S) wave that will hit, say, Los Angeles a few minutes afterwards. The forecast would give residents perhaps only a few seconds of advanced notice, but that could be enough time to exit an elevator or move away from windows.

"We're talking about seconds, but in some instances they can be very valuable seconds," Jackson said. "Sometimes it could be enough to save your life."

The researchers are now working to incorporate the sensors into early warning systems for hospitals and bridges, and would like to expand the sensor network to cover the entire west coast.